Reproducer for phonographs



NOV. 17, 1936. L, D, NORTON 2,061,475 I REPRODUQER FOR PHoNoGRAPHs original Filed April 15, 1935 '2 sheets-sneu 1 u if l INVENTOR j ATTORNEYS Nov. 17, 1936. L.. D. NORTON REPRODUCER FOR PHONOGRAPHS Original Filed April 15, 1935 2 Sheets-Sheet 2 INVENTOR Lelgmcl No1-0n mf/m LW ATTORNEYS Tri .E11

REPRODUCER FOR PHONOGRAPHS Leland D. Norton, Bridgeport, Conn., assignor to Dictaphone Corporation. New York, N. Y., a corporation of New York Application April l5,

1935, Serial No. 16,437

Renewed January i8, 1936 10 Claims.

This invention relates to acoustic reproducers for phonographs and more particularly to improved means for modifying the sound transmitted thereby. An object of the invention is to 5 provide an efficient reproducer and modifier device of simple and compact form and construction. A further object is to provide a sound modifier effectively operable gradually to vary tone and intensity of sound transmitted thereby. Other objects Will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of the various possible embodiments of my invention:

Fig. 1 is a sectional view through a portion of a transcribing machine carriage showing the sound-box and sound-modifier mounted thereon. This section is taken on line l-l of Fig. 5.

Fig. 2 is a cross-section of the modier taken on line 2-2 of Fig. l;

Fig. 3 is a horizontal cross-section of the modiiier taken on line 3-3 of Fig. 2; n

Fig. l is a horizontal cross-section of the modier taken on line i-fl of Fig. 2;

Fig. 5 is a top plan view of the modifier;

Figs. 6, 7, 8 and 9 are diagrammatic views showing the relation of the vent port in relation to the valve at successive stages as the modier occupies Loud, Medium, Soft and Oli positions.

Similar reference characters refer to similar parts throughout the several views of the drawings.

As is well known, in the operation of transcribing phonographs the vibrations of a diaphragm, caused by a stylus following the sound track of a sound-record, eiect in the sound-box of the machine a succession of sound waves having substantially the same characteristics as those which were recorded upon the phonograph record. These sounds are transmitted from the soundbox through a sound passage associated with the sound-box and ultimately reach the operators ears through hearing devices of suitable construction.

The amplitudes of soun waves thus produced by the diaphragm vary greatly with different records and consequently the volume of sound reaching the ears of the operator also is greatly variable.

It is, therefore, advantageous to provide a modier for the purpose of controlling the sound intensities produced by vdifferent records so that the sound received by the operator may be held at a uniform or desirable loudness, by merely adjusting the modifier.

It has been found that when the sound passage through a modifier is merely restricted to reduced volume, the sound becomes hollow or muffled because of the disproportionate loss of the sound waves having the higher frequencies. This effect is not produced when the sound is modiiied by simultaneously allowing a sufficient portion of the energy of the sound waves to escape. to the atmosphere. However, a nice balance must at all times be maintained between the degree of restriction of the sound passage and the quantity of sound energy permitted to escape. Heretofore modiiiers have been constructed having the characteristic of accomplishing simultaneously a gradual closing of the sound air passage and a gradual opening of the vent passage to the atmosphere. The results attained with such modifiers have not been uniformly satisfactory, due no doubt in many instances to the inclusion of large resonant pockets in the sound passages. Where such pockets exist, and in fact where they do not exist but the air passages themselves are of large volume, it has been found that the resonant effect produced by succeeding sound waves increases rapidly as the sound passage is restricted ahead of the advancing Waves. It was therefore thought necessary to increase the vent opening at the same time that the sound passage was diminished.

Experiment has recently revealed the fact that Where the sound passages are. properly designed by making them as straight as possible and freeing them from resonant pockets, best results are attained by gradually decreasing the amount of venting simultaneously with a gradual restriction of thesound passage. And this result, although contrary to pre-existing opinion, is not surprising when notice is taken of the fact that restrictio-n of the sound passage tends to build up sound wave energy in the sound passage back of the restricted portion thereof. As a consequence the rate at which the sound energy escapes to the atmosphere through the vent opening increases Now referring to the drawings, the carriage IIJ of a transcribing phonograph is provided with an opening I I in which lits the reproducer and modifier unit, indicated generally by I2. This unit comprises a shallow annular sound-box I3 and a modifier housing I4, the latter seated in a recess I5 formed in the upper part of the former and held in position relatively to the sound-box by means of a set screw I6. The sound-box of the reproducer is provided with a vibratory diaphragm Il to which is connected a link I8 to actuate a stylus-carrier (not shown) the stylus of which is adapted to track the sound groove of a phonograph record. The vibrations of the diaphragm produced by the phonograph record set up in the air chamber I9 of the sound-box a succession of sound-waves of substantially the same character as those which were recorded.

In the present embodiment the modier comprises the above mentioned housing I 4 and a cylindrical valve member 20 rotatably seated in snug relation to the walls of a cylindrical chamber 2l, which chamber extends through the housing I4 and is open at both upper and. lower ends. This chamber is connected to the air chamber I9 within the sound-box by means of an inlet passage 22, of restricted diameter relatively to the diameter of the air space I9. The valve chamber 2I is slightly larger in diameter than the passage 22, and the Valve cylinder 20 is provided with a passage 23 of substantially the same diameter as the inlet passage 22 coaXially aligned with the said passage 22 and forming a direct continuation thereof. The passage 23 extends upwardly in the valve member a sulcient distance to intersect with an upwardly inclined passage 24, adapted to be brought into alignment with an upwardly inclined outlet passage 25, provided by a tubular member 26 extending through the peripheral wall of the housing I4.

It will be noted that the relation of the outlet passage 25 to the cylindrical valve chamber 2I and also the relation of the valve passage 24 to the Valve passage 23 is such that their axes intersect in an angular relation greater than 90. This arrangement is advantageous in that it eliminates sharp bends in the sound passage. Since, at the junction of the sound passages within the valve member the adjoining walls are curved at as great a radius as is practicable, there is attained, as a result, a passageway from the inlet passage 22 to and through the passageway 25 which is free from sharp bends or other obstructions tending to cause reverberation or produce resonant effects as the sound Waves are carried from the diaphragm to the ears of the operator. The tubular member 26 may be connected in the usual manner with hearing devices by means of rubber tubing.

At its upper end the valve member is provided with a ilat cap portion 2'I, which, covering the upper end of the housing I4, extends beyond the peripheral walls thereof and provides eicient means for rotating the modifier Valve. Occupying positions 90 apart upon the upper surface of the cap appear the index markings Loud, Med, Soft and Off (see Fig. 5) to indicate the appropriate positions of the valve for loud, medium or soft transmission, and for the completely closed position. These index marks are adapted to be brought respectively into line with a pointer member 28 mounted upon the housing I4.

By reference to Figs. l, 3 and 4 it will be seen that the housing I4 has formed therein, extending down from the upper surface thereof, a deep recess 29 seated in the bottom of which is a helical spring 30 adapted at all times to press upwardly against the bottom of a plunger 3| tting sliclingly within the recess 29. When the valve cylinder is assembled in operative relation to the housing I4 this spring presses against the underside of the valve cap portion 21. The Valve is held against axial movement within the housing I4 by means of a screw 32 the inner end of which fits closely between the side walls of an annular groove 33 formed in the valve cylinder 20. The plunger SI resiliently holds the valve groove in such relation to the screw 32 that the valve and housing passages 24 and 25 respectively may be brought into full registry one with the other when the Valve member is turned so that the Loud indication upon the cap is opposite the pointer 28. A stop pin 34 seated in the groove 33 engages alternatively the inner end of the screw 32, on oppositey sides, to determine the limit positions of the valve, those positions being the Loud and Off positions. The spring 35 holds the plunger 3! against the cap 2 with sufficient pressure so that the Valve is frictionally held in any adjusted position.

Seated in the plane of the horizontal axis of the orifice of valve passage 24 there is shown a V-shaped groove 35 cut in the peripheral wall of the valve cylinder 20, which, starting with a predetermined depth where it intersects the passage 24, extends away from the passage in a clockwise direction as seen in Figs. 1 and 3, and gradually grows shallower until it runs out at a predetermined point indicated in Fig. 3 by the reference numeral 36.

Referring to Fig. 1, a vent opening 3'I extends horizontally through the lower portion of the housing I4 and the surrounding wall of the sound-box, connecting the Valve chamber 2I with the outer atmosphere. It will be noted that the location of this vent passage is closely adjacent the inlet passage 22 from the sound-box. Since it is desirable to cause a gradual cutting off of communication from the interior of the valve to the atmosphere, through this vent port, at the same time that the sound passager is being restricted by bringing the V-groove 35 into direct communication with the outlet passage 25, the lower end of the Valve cylinder is truncated or cut away helically, as illustrated at 38, to provide an advancing helical wall surface capable of being turned across the inner end of the port 3'I to control the venting of air through that port.

Reference to Fig. 6 will show the position of the helically cut end of the valve member relatively to the vent port 3l when the valve member stands in the position disclosed in Figs. 1, 2 and 3, namely, in the position for loud transmission with the passage through the valve in full registry with the passage 25. In this position of the ports the Vent opening is in full communication with the interior of the Valve member and with the inlet passage 22. As shown in Fig. 'l'. the valve has been turned in a counter-clockwise direction from Loud to Med.. In this position of the parts the sound passage will be partially restricted, the sound passage 24 having passed out of registry with the passage 25 so that the deeper portion of the V-groove 35 serves to conduct the sound waves from the interior of the valve to the interior of the passage 25. Concomitantly with this restriction of the sound passage, the Vent passage will have been partially closed. A further quarter-revolution brings the valve to the Soft position, indicated in Fig. 5, when -communication between the inlet valve passage and the valve housing passage will be only by means of the shallow end portion of the V-groove 35. At this time only limited venting will be permitted as indicated by the position of the end wall of the valve member relatively to the vent port in Fig. 8. A further quarter-turn will completely close communication both between the sound passage and outlet 25 and between the valve passage and vent port 31.

It will be seen that there is provided a construction oi an essentially practical nature in which the several objects of this invention are attained.

As many possible embodiments may be made of the above invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a sound modifier of the character described, in combination, a pair of relatively movable members provided with registrable passages, means for providing gradually decreasing communication between said passages as they are moved out of registry, means for simultaneously providing gradually decreasing communication between one of said passages and the outside atmosphere, and means for relatively moving said members.

2. In a sound modier of the character described, in combination, a valve housing, a tubular valve member rotatably mounted in said housing and having an end cut away to provide a gradually advancing wall surface, a vent port in said housing adapted to be gradually opened or closed to the interior of said valve member by said wall surface upon rotation of said valve member, and means for rotating said valve member.

3. In a sound modifier of the character described, in combination, a valve housing, a tubular valve member rotatably mounted in said housing and having an end cut away to provide a helically advancing wall surface, a vent port in said housing adapted to be gradually opened or closed to the interior of said valve member by said wall surface upon rotation of said valve member, and means for rotating said valve member.

4. In a sound modier of the character described, in combination, a pair of inner and outer members relatively rotatable about a common axis and provided with registrable sound passages, one of said members being formed with a helically advancing wall surface adapted to cooperate with a vent port in the other of said members upon relative rotation being imparted to said members to gradually open or close said passage to the outside atmosphere, and means for eiecting relative rotation of said members.

5. In a sound modier of the character described, in combination, a housing having formed therein a cylindrical valve chamber communicating with a coaxial inlet passage at an end of the housing and an outlet passage extending laterally through said housing, the relative positions of said passages being such that their axes intersect at an obtuse angle, a cylindrical valve rotatably mounted in said valve chamber having formed therein connecting passages which in a certain position of said valve are respectively coaxial relatively to the said inlet and outlet passages and communicate therewith, and means for maintaining restricted communication between said connecting passages and said outlet passage when said valve` is turned away from said certain position.

6. A sound modier comprising sound-transmitting means, sound-venting means having free access to the atmosphere, and an adjustable valve member for coordinately effecting a gradual closing of both the sound-transmitting and the sound-venting means at a single operation.

7. A sound modifier comprising sound-transmitting means, sound-venting means having free access to the atmosphere, and an adjustable valve member for coordinately effecting a gradual closing of both the sound-transmitting and the sound-venting means at a single operation or effecting a gradual opening of both said means at a single operation.

8. In a sound modifier of the character described, in combination, a substantially unrestricted continuous sound passage, a housing member having an inlet port communicating directly with one end of said sound passage and an outlet portA adapted during movement of said valve in one direction to communicate with the other end of said sound passage through an increasingly indirect path, a vent port in said housing adjacent said inlet port, and means on said valve member for gradually cutting off communication between said vent and inlet ports during the said movement of said valve.

9. A sound modifier comprising a casing having a sound transmitting opening, a sound venting opening free to the atmosphere and means mounted in said casing for varying the extent of said openings simultaneously in the same sense.

10. A sound modifier comprising a casing having a sound transmitting opening, a sound venting opening free to the atmosphere and a valve for coordinately effecting gradual variation of the extent of said sound transmitting and said sound venting openings in the same sense at a single operation.

LELAND D. NORTON. 

